1. Chemistry 123 Spring 2008 Dr. Woodward
An introduction to the Pigment Research Project Light, Color and Pigments
Chemistry 123
Spring 2008
Dr. Woodward

2. Ohio REEL Project Research Experiences to Enhance Learning
Partner Institutions
University of Akron (UA)
Bowling Green State University (BGSU)
Capital University (CU)
Central State University (CtlSU)
University of Cincinnati (UC)
Cleveland State University (CSU)
Columbus State Community College (CSCC)
University of Dayton (UD)
Kent State University (KSU)
Miami University of Ohio (MU)
Ohio University (OU)
University of Toledo (UT)
Wright State University (WSU)
Youngstown State University (YSU)
The Ohio State University (OSU)
Supported by the National Science Foundation

3. How does a research module differ from a “normal” lab
Research exploration
Outcome is not known in advance
Involves all phases of the research process
Form a hypothesis
Conduct experiments to test hypothesis
Interpret & report results
Modify hypothesis
Tackles problems of societal interest
Chemistry plays a central role in many challenges facing society
Builds on previous experiments
The details of the experiment evolve from year to year

4. Research Timeline Week of Mon/Tue Lab Wed/Thur Lab April 28
REEL-I,II & III
May 5
REEL-III & IV
REEL-IV
May 12
REEL-I: Use X-ray fluorescence (XRF) and X-ray powder diffraction (XRPD) to identify an unknown salt
REEL-II: Use UV-Visible (UV-Vis) spectroscopy to probe the electronic structures of transition metal complexes in solution
REEL-III: Use solid state reactions to prepare pigments, characterize the composition, crystal structure and electronic structure of the pigments using XRF, XRPD and UV-Vis methods.
REEL-IV: Build on the ideas developed in REEL-III to prepare and characterize inorganic pigments of your own design.

5. Logistics Research will be conducted in teams
Students will work in teams (~4 students per team)
Research will be pursued collaboratively
Dr. Woodward & Dr. Stoltzfus
REEL Lab Coordinator (Harry Seibel)
Teaching Assistants
Peer Mentors
Research presentation
Each research group will present their results at one of three REEL poster presentations (May 20,21,22)
Research documentation and reporting
Each student will prepare a report in the form of a scientific paper to describe their research findings

6. Peer Mentors
Back Row: Lana Alghotani, Sachin Sharma, Jen Scherer, Alex Paraskos, Eric Smith, Sarah Watson, Ashley Doles, Derek Heimlich, David Albani, Front Row: Jalpa Patel, Sam Karnitis, Gina Aloisio, Stephen Smith, Brittany Thompson, Ravi Rajmohon, Ken Verdell, Amy Ullman, Amy Tucker, and Kristen Brandt

7. Experimental Methods Synthesis Characterization
Direct solid state reactions
Characterization
X-ray powder diffraction
X-ray fluorescence
UV-Visible Spectroscopy
Ocean Optics UV-Visible Spectrometer (~$7,000)
X-ray Powder Diffractometer (~$65,000)

8. For more info see http://webexhibits.org/pigments/
Pigments
Pigment: Coloring matter used to make paint.
Pigments work by selectively absorbing a portion of the visible light while the remaining visible light is reflected.
For more info see

9. For more info see http://webexhibits.org/causesofcolor/
Causes of Color
Emitted Light
Blackbody Radiation, Incandesence (light bulb, flame)
Gas Discharges/Excitations (neon lights, aurora borealis)
Luminescence (LED’s, fluoresecent lights, chemluminescence)
Steering and/or Interference Effects
Dispersive Refraction (rainbows, prisms)
Scattering (blue sky)
Interference & Diffraction (butterflies, beetles, opals, CD’s)
Absorbed Light
Intra-atomic excitations (Complex ions, gemstones)
Molecular Orbital Excitations (Chlorophyll, organic dyes)
Band to Band Transitions in Semiconductors (CdS, SnS2, HgS)
Interatomic (charge transfer) excitations
Oxoanions (i.e. CrO42−, MnO4−), Pigments (Prussian blue, chrome yellow), gemstones (sapphire)
For more info see

10. The Electromagnetic Spectrum
Violet
Blue
Green
Yellow
Orange
Red

11. Properties of Electromagnetic Radiation (Light)
Quantity
Units
Energy, E
Joules
Frequency, n
1/s or Hz
Wavelength, λ
meters
Speed of Light, c
2.998  108 m/s
Planck’s constant, h
6.626  10−34 J∙s

12. The Color Wheel 1 eV = 1.602  10−19 J UV 100-400 nm 12.4 - 3.10 eV
Violet nm eV
Blue nm eV
Green nm eV
Yellow nm eV
Orange nm eV
Red nm eV
Near IR , nm eV
1 eV =  10−19 J

13. Absorption of Light & Color
If absorbance occurs in one region of the color wheel the material appears with the opposite (complimentary color).
a material absorbs violet light  Color = Yellow
a material absorbs green light  Color = Red

14. Absorption of Light & Color
If absorbance occurs in multiple regions of the color wheel the material generally takes on a color in the middle of the colors that are not absorbed.
a material absorbs violet, blue and green light  Color = Orange
a material absorbs violet and red light  Color = Yellow-Green

15. UV-Visible Spectroscopy
Monochromatic light (light of a single wavelength) is passed through the sample and the amount of light absorbed by the sample is measured.

16. Color and Cu2+ complexes
[Cu(H2O)4]2+
[Cu(NH3)4]2+